Silencing of P2Y(2) receptors reduces intraocular pressure in New Zealand rabbits.

BACKGROUND AND PURPOSE

P2 receptors are involved in the regulation of ocular physiological processes like intraocular pressure (IOP). In the present study, the involvement of P2Y(2) receptors in the hypertensive effect of nucleotides was investigated by use of antagonists and of a siRNA designed for the P2Y(2) receptor.

EXPERIMENTAL APPROACH

Agonists of the P2Y(2) receptor a as well as P2 antagonists were applied to eyes of New Zealand rabbits, and the changes in IOP were followed for up to 6 h. Cloning of the P2Y(2) receptor cDNA was done using a combination of degenerate reverse transcription PCR (RT-PCR) and rapid amplification of cDNA ends (RACE). siRNA was synthesized and tested by immunohistochemistry.

KEY RESULTS

Single doses of 2-thioUTP, UTP-γ-S and UTP increased IOP. This behaviour was concentration-dependent and partially antagonized by reactive blue 2. Silencing the P2Y(2) receptor was observed in the ciliary body by immunohistochemistry labelling, where a reduction in the immunofluorescence was observed. This reduction in the expression of the P2Y(2) receptor was concomitant with a reduction in IOP, which was measurable 24 h after treatment with the siRNA, maximal after 2 days, followed by a slow increase towards control values for the following 5 days. Application of the P2Y(2) agonists after pretreatment of the animals with this siRNA did not produce any change in IOP.

CONCLUSIONS AND IMPLICATIONS

P2Y(2) receptors increase IOP in New Zealand rabbits. The application of a siRNA for this receptor significantly reduced IOP, suggesting that this technology might be used for the treatment of glaucoma.